This invention relates to a support tube for an office chair, particularly to one provided with a comparatively good lubricating effect, with lubricating oil not flowing out of the support tube.
Generally speaking, a support tube for a conventional office chair, as shown in FIG. 1, not only supports a seat A and connected between the seat A and a base frame C, but also enables the seat A rotate for 360 degrees so as to adjust the height of the seat A to suit the body height of a user.
The support tube for a conventional office chair, as shown in FIG. 2, includes an outer tube D, an inner tube E fitted in the outer tube D, and a shaft F fitting movably in the inner tube E and fixed with a lower end of the outer tube D at its lower end. And an upper end of the shaft F is fixed firmly with the bottom of the seat A.
However, rotation of the seat A and adjustment of the seat height is effected by means of lubricating oil filled on an outer surface of the shaft F and an inner surface of the inner tube E. But as the outer surface of the shaft F and the inner surface of the inner tube E closely fit with each other, without any aperture for lubricating oil to stay thereon and to liable to overflow out of the inner tube E. Then the shaft F and the inner tube E may not get good lubricating effect.